Took some time to work out how to do it but have now 2 separate 3x2 images superimposed on a landscape image at A4 (i.e. 3 images printed on one A4 sheet). The 3x2s are oval fade cutouts but I cannot find a way for the fade to fade to background i.e. the A4 image. It currently fades from its image to a white background thereby retaining the overall 3x2 box.

In the current version, you can only fade to a single (chosen) color. You cannot fade to a print that is behind another print. We're working on things like that, plus the ability to rotate images without showing a white background for future versions.